Microbiology for usmle - quizlet Flashcards
N. meningitis
Gram- coccus, ferments maltose
S. Aureus
Gram+ coccus, catalase+, coagulase+
S. Pyogenes, S. Agalactiae
Gram+ coccus, catalase-, B-hemolysis
S. epidermitis, S. saprophyticus
Gram+ coccus, catalase+, coagulase-
S. Pneumoniae, S. Viridans
Gram+ coccus, catalase-, a hemolysis
Enterococcus
Gram+ coccus, catalase-, y hemolysis
S. Pneumoniae
Gram+ coccus, catalase-, bile soluble
S. Pneumoniae
Gram+ coccus, quellung+
Listeria
Gram+ rod, has endotoxin
Clostridium, Bacteroides, Actinomyces
Aminoglycosides are ineffective
K. Pneumoniae, Salmonella, HiB
Gram- rod, quellung+
C. diptheriae
AB toxin inactivates EF-2
ETEC
AB toxin (1) activates adenylate cyclase (=> cAMP); AB toxin (2) stimulates guanylate cyclase
B. pertussis
AB toxin inhibits G(i) protein => increased cAMP
C. diptheriae
Has an AB toxin that is similar to Pseudomonas exotoxin A in effect
B. anthracis
Has edema factor (=> cAMP)
Streptolysin O
Antibody used to dx RF
C. botulinum
Blocks Ach release
C. tetani
Blocks GABA and glycine release
S. pneumoniae, HiB, N. meningitis
Has bacterial competence
Listeria
Gram + rod, B hemolysis
S. Aureus, other catalase producing organisms
Affects those with chronic granulomatous disease
S. pneumoniae
Rusty sputum. Causes sepsis in those with sickle cell anemia, and asplenic patients
S. pneumoniae, HiB, N. meningitis
Has IgA protease
S. pyogenes
Avoids phagocytosis using M protein
S. bovis
Causes bacteremia and subacute endocarditis in colon cancer patients
Clostridium, B. anthracis
Gram+ rod, spore forming
B. anthracis
Has a polypeptide capsule with D-glutamate
Actinomyces israelii
Forms sulfur granules in sinus tracts
M. leprae
Gram+ bacillus, grows in live cells only.
M. leprae (lepromatous form)
Loss of eyebrows, nasal collapse, lumpy earlobe
K. pneumoniae, E. coli
Gram- rod, lactose fermenter
Pseudomonas
Gram- rod, non-lactose fermenting, oxidase+
Shigella, Salmonella, Proteus
Gram- rod, non-lactose fermenting, oxidase-
Gram- rods
Resistant to penicillin G and vancomycin, but may be sensitive to derivative (ie ampicillin)
H. influenza
Requires NAD and hematin for growth
Legionella
Gram- rod, requires silver stain for visualization
Legionella: erythromycin
Gram- rod, needs iron and cysteine for growth. Treat with?
Pseudomonas: aminoglycoside + extended spectrum PCN
Causes malignant otitis externa in diabetics. Treat with?
Pseudomonas
Produces exotoxin A => inactivates EF-2
Enterobacteria. All are lactose fermenters and oxidase negative
Have O, K, and H antigens
EHEC
Has a Shiga-like toxin. Causes necrosis and inflammation. Does not invade mucosa.
EPEC
Gram- rod. Causes diarrhea by flattening villi - no toxin. Associated with clusters.
K. Pneumoniae
Causes aspiration pneumoniae, lung abscesses. Infects alcoholics and diabetics. Also causes nosocomial UTI
EIEC
Has a Shiga-like toxin, but mucosal invasion is what causes necrosis/inflammation.
Typhoid fever, caused by Salmonella typhi
Fever, diarrhea, HA, rose spots on abdomen
Salmonella
Non-lactose fermenting gram-rod; has flagella and produces H2S
Salmonella
Remains in gallbladder chronically
Yersinia enterocolitica
Mimics Crohn’s and appendicitis. Major source: pigs
H. pylori
Gram- rod, urease+. Risk factor for peptic ulcer, gastric adenocarcinoma, and lymphoma
Spirochetes
Visualized with dark field microscopy
Borrelia burgorferi: Ixodes tick: doxycycline, ceftriaxone
Causes erythema migrans, bilateral Bell’s palsy, AV block, and arthritis. Source? Treat with?
Whipple’s disease (T. whippeli)
Visualized with PAS stain
ETEC (often with campy)
Common cause of Traveler’s diarrhea
Secondary syphilis
Maculopapular rash on palms and soles, condylomata lata
Tertiary syphilis
Chronic granulomas, aortic valve insufficiency, tabes dorsales destruction (ataxia, +Romberg, Charcot joints, stroke w/o HTN)
Congenital syphilis
Saber shins, saddle nose, Hutchinson’s teeth, deafness, mulberry molars
Tertiary syphilis
Argyll Robertson pupil
VDRL
Reacts with beef cardiolipin. Can be positive in Viral infxn, drugs, RF, Lupus/leprosy, and syphilis
Brucella
associated with unpasteurized dairy products/animals. causes undulent fever.
Francisella tularensis
associated with rabbits and deer. requires cysteine for growth. causes ulcers.
Pasteurella multocida
cellulitis associated with animal bites (esp cats and dogs)
Gardnerella vaginalis: metronidazole
Gram variable rod. Overgrowth of bacteria => fishy smell. Clue cells are visible under microscopy. Treat with?
Rickettsiae: TCN
Obligate intracellular organisms that cause a triad of HA, fever, and a rash. +Weil Felix reaction. Treat with?
R. rickettsii (rocky mountain spotted fever)
Rash starts on hands and feet, spreads inwards. Transmitted via tick.
R. typhi
Rash starts centrally and spreads outwards. Does NOT involve palms or soles
Coxiella burnetii
Inhalation of this causes pneumonia (“Q fever”). -Weil Felix reaction
Chlamydiae: erythromycin or TCN
Obligate intracellular organism. Has two forms, elementary body and reticulate body. Treat with?
Chlamydia psittaci
Atypical pneumoniae, has an avian reservoir
Chlamydia trachomatis types L1-3
obligate intracellular organism, +Frei test. causes lymphogranuloma venereum
Chlamydia trachomatis types A, B, C
obligate intracellular organism, causes blindness in Africa
Chlamydia trachomatis types D-K
obligate intracellular organism, causes reactive arthritis, conjunctivitis, urethritis, PID, ectopic pregnancy
M. pneumoniae: TCN/erythrocyclin (PCN resistance d/t no cell wall)
Classic cause of “walking pneumoniae”. High amt of IgM. Treat with? Why?
Histoplasmosis
pneumonia associated with bat droppings (cave spelunking). location: Mississippi, Ohio river valleys. yeast is smaller than RBC.
Blastomycosis
pneumonia, forms granulomatous nodules. location: SE united states. yeast is same as as RBC
Coccidioidomycosis
pneumonia and meningitis associated with earthquakes. location: SW united states. yeast is larger than RBC
Paracoccidioidomycocis
captain’s wheel appearance (budding yeast, larger than RBC)
Tinea versicolor
spaghetti and meatball appearance on KOH prep.
Malassezia furfur
causes hypopigmented patches on skin
dermatocytes (Microsporum, Trichophyton, Epidermophyton): Tinea pedis, cruris, corporis, capitis
causes pruritic lesions with central clearing
Aspergillus
monomorphic mold, with hyphae that branch at angles <45 degrees. especially affects immunocompromised and those with chronic granulomatous disease
Cryptococcus neoformans
Encapsulated yeast. found in pigeon droppings. “Soap bubble” lesions in brain
Mucor and Rhizopus
Dimorphic. Mold has branched hyphae at angles >90 degrees. Afects DKA and leukemia patients. Fungus proliferates in blood vessels => infarct, necrosis.
Candida albicans: nystatin (superficial) or amphotericin B (serious/systemic)
Germ tube formation at 37C. Treat with?
Pneumocystis jiroveci: TMP-SMX: CD$ <200
Diffuse interstitial pneumonia in immunosuppressed. Treat? When to prophylaxis?
Sprothrix schenckii
Dimorphic fungus. Causes ascending lymphangitis (ulcers). Cigar-shaped budding yeast.
Giardia lamblia: metronidazole
Foul-smelling, fatty diarrhea. Often encountered in hikers. Treat with?
Entamoeba histolytica: metronidazole/iodoquinol
Liver abscess, bloody diarrhea. Histology: flask-shaped ulcer. Treat with?
Cryptosporidium: water sanitation
Watery diarrhea; severe in AIDS. Acid-fast cysts. Treat with?
Toxoplasma: TMP-SMX
Brain abscess (HIV): ring-enhancing lesions. Treat with?
Congenital Toxoplasma
Chorioretinitus, hydrocephalus, intracranial calcifications
Naegleria fowleri
Rapidaly fatal meningoencephalitis. From swimming in freshwater lakes
Trypanosoma cruzi: reduviid bug (kissing bug)
Dilated cardiomyopathy, megacolon, megaesophagus. Transmitted via?
Trypanosoma gambiense/rhodesiense: Tsetse fly
Enlarged lymph nodes, recurring fever, EDS, insomnia, coma. Transmitted via?
Leishmania donovani: sandfly
Spiking fevers, hepatosplenomegaly, pancytopenia. Transmitted via?
Plasmodium: Anopheles mosquito: Chloroquin (+Primaquine if vivax/ovale)
Malaria: cyclic fever, HA, anemia, splenomegaly. Transmitted via? Treat with?
Babesia: Ixodes tick: Quinine/clindamycin
Fever, hemolytic anemia. Blood smear shows maltese cross. Transmitted via? Treat with?
Trichomonas vaginalis: metronidazole
Foul smelling, green vaginal discharge. Itching and burning. Treat with?
Enterobius vermicularis (pinworm)
Anal pruritis
Ascaris (roundworm)
Helminth; Eggs are visible in feces
Trichinella spiralis
Larvae encyst in muscle; periborbital edema. Usually found in undercooked pork
Strongyloides stercoralis
Larvae in soil penetrate skin => GI, causing vomiting, diarrhea, anemia
Ancylostoma duodenale, Necator americanus (hookworm)
Larvae penetrate feet => GI. Sucks blood from intestinal walls => anemia
Onchocerca volvulus: blackflies
hyperpigmented skin, river blindness. Transmitted via?
Loa loa
Can see worm crawling in conjunctiva
Wuchereria bancrofti
causes elephantiasis
Toxocara canis
causes granulomas, visceral larva migans. If in retina => blindness
Taenia solium
Ingestion => tapeworm (if larvae) or cysts in brain (if eggs)
Diphyllobothrium latum
Larvae in raw freshwater fish => B12 deficiency, anemia
Echinoccous granulosus
Eggs in dog feces, => anaphylaxis. Must inject ethanol before removal of cysts.
Schistosoma
Cercariae => granuloma, fibrosis, inflammation of spleen/liver (portal HTN). Chronic infxn => squamous CC of bladder
Clonorchis sinensis
Undercooked fish => cholecystitis => pigmented gallstones. A/w cholangiocarcinoma
Paragonimus westermani
Undercooked crab => inflammation, infection of lung => hemoptysis
lactobacillus
normal flora of vagina
bacteroides
normal flora of colon
s. mutans
dental plaques
vibro
food poisoning a/w seafood
b. cereus
food poisoning a/w reheated rice
c. perfringens
food poisoning a/w reheated meat
c. botulinum
food poisoning a/w improperly canned food
e coli O157:H7
food poisoning a/w undercooked meat
salmonella
food poisoning a/w poultry, eggs
s. aureus
food poisoning a/w custard, meat, mayo. preformed toxin.
S. pneumo, K. pneumo, staph
pneumonia a/w alcoholics or IV drug users
psuedomonas
a/w cystic fibrosis
listeria
causes meningitis in newborns and elderly
s. aureus
MC cause of osteomyelitis
pseudomonas
osteomyelitis in diabetics, drug addicts
salmonella
osteomyelitis in those with sickle cell
pasteurella
osteomyelitis from cat/dog bites/scratches
n. gonorrhea/septic arthritis
osteomyelitis in sexually active
leukocyte esterase (=> bacterial); nitrite (=> gram-)
diagnostic markers for UTI
s. aprophyticus
2nd lead causing of community acquired UTI in sexually active women
congenital rubella
PDA, cataracts, deafness, “blueberry muffin” rash
congenital CMV
hearing loss, seizures
congenital HIV
recurrent infxn, chronic diarrhea
congenital HSV
encephalitis, herpetic lesions
syphilis
often results in hydrops fetalis
Haemophilus decreyi (chancroid)
painful genital ulcer, inguinal adenopathy
HSV2
painful penile, vulvar, or cervical ulcers. can cause systemic sx
chlamydia, gonorrhea
chandelier sign - MC causes?
Trichomonas
vaginitis, strawberry cervix
HiB
fever with dysphagia, drooling, difficulty breathing. cherry red epiglottis
c. diptheriae
grayish oropharyngeal exudate
poliovirus, Hib
meningitis, may lead to myalgia and paralysis
bartonella henselae
superficial vascular proliferation